Execution

Devil's Slide is located south of the City of Pacifica in California along the coastal road of Highway 1. Landslides and grade subsidence in the Devil's Slide area along Route 1 have led to the road being closed for extended periods causing significant economic loss to the surrounding communities. The solution: Construct a tunnel through the mountain to bypass the dangers and reoccurring problems. Construction of 1250m twin tunnels, 9m wide, 6.8m high using Sequential Excavation Method (SEM). Additionally, drill and blast and roadheader excavation through weathered rock utilised.

Bond Street Station serves an interchange between the Jubilee Line, the Central Line and the future Crossrail Station. New tunnels including access and lift shafts, construction adits, binocular cross passage tunnels, large concourse and connection chambers, underpass and over-bridge tunnels cutting through existing platform tunnels, and an inclined escalator tunnel were constructed in very close proximity to existing London Underground structures.

The major upgrade to the LU Tottenham Court Road Station has been proposed to relieve congestion, achieve step-free access and modernise the station. The major elements of the station upgrade comprised a new enlarged sub-surface ticket hall, a fire-fighting access / emergency escape shaft linked to both Central and Northern lines, a triple escalator barrel, and concourses to the Northern and Central lines. In the latter concourse two new overbridges were included to lead to the platforms via new stairs and lifts. For the tunnelling works, a particularly challenging part was to design and construct the two SCL overbridges over the operational Central line.

Contract C305 is the biggest design-bid-build construction contract of the Crossrail (CRL) project and includes the eastern running tunnels of CRL's central section with launch shafts and SCL launch adits for TBMs at Limmo Peninsula, SCL caverns and launch adits for TBMs at Stepney Green and 10 SCL cross passages between the running tunnels with lengths up to 30m. At the Limmo Peninsula site a 40m deep and 30m diameter SCL shaft was built. At the shaft bottom in Stepney Green, two 30m long and up to 10m wide SCL launch adits were constructed followed by two 14m high and up to 18m wide, SCL caverns with single sidedrift and double sidedrift cross sections.

Farringdon station is now one of London's major rail interchange stations, providing connections between three networks. During the construction of the Crossrail project, it also received four earth pressure balanced tunnel boring machines (TBMs): the two Drive X TBMs, running from Royal Oak to Farringdon and the two Drive Y TBMs, running from Limmo to Farringdon. The complete station layout will comprise two ticket halls, two platform tunnels, connecting cross passages, escape and ventilation adits, two escalator - inclines and two concourse tunnels constructed using mainly SCL tunnelling.

The Bergen Tunnel on the New Jersey Transit network is a double track, horseshoe shaped rail tunnel, built in the 1870s, passing through fractured diabase. Over time, water ingress has caused operational problems. In 2000 the owner decided to undertake major structural rehabilitation. The brick lining was stripped out and the original profile was enlarged to take a new reinforced in-situ concrete lining and drainage system. Old ventilation shafts were backfilled. Two large openings were retained for tunnel ventilation, emergency access and to house new power and electrical substations.

The Santiago Metro network comprises five lines. The Linea 2 South extension included 2.5km dual track running tunnels and two stations with a maximum span of 16.2m. Further, an excavation of 60-65m2 running tunnel in combined top heading/bench with a subsequent invert excavation. Reinforcement consisted of lattice girders, welded wire fabric for initial lining and welded wire fabric for final shotcrete lining. Dr. Sauer and Partners assisted in the production of design criteria for the final design and produced finite element structural computations for the large station caverns.

The Corsica Street Ventilation Shaft comprises the permanent pressure relief and ventilation adit connecting the down line running tunnel to the shaft and temporary access adit tunnel. The ventilation adit was designed as a permanent sprayed concrete lined tunnel built in two phases: primary and secondary linings. The required watertightness was reached by staggering the joint locations between primary and secondary linings, utilising internal curing agents and steel fibres in the secondary lining sprayed concrete and injecting flexible tubes into joints of the secondary lining.

The Cumberland Gap Tunnels are two dual-lane highway tunnels with a length of 1300m each, connecting Kentucky and Tennessee through the Cumberland Mountains. Because of the complex, variable geology and economic considerations, the New Austrian Tunneling Method (NATM) was chosen. The tunnel design included five excavation and support classes with rock dowels, lattice girders and reinforced shotcrete as primary lining. The final lining for the twin tunnels and 13 cross passageways was designed as cast-in-place (CIP) concrete with a flexible membrane waterproofing system.